Month 4 — Greedy & Systems

Weeks 16+. Greedy with exchange-argument proofs, binary-search-on-answer, and the bridge to practical engineering problems.

Weeks

• Week 16 — Greedy Mastery & Exchange Arguments: Queue Reconstruction (2D sort key), Gas Station (failure-skip lemma), Task Scheduler (heap vs closed form), Burst Balloons (interval scheduling), Split Array Largest Sum (binary search on answer).

Why this month

Greedy is the most dangerous interview category — wrong greedy choices pass the obvious tests and fail silently on the cases that matter. This month focuses on proving greedy correct via exchange arguments and recognizing when binary-search-on-answer is the right tool. The Staff/Principal signal here is justification, not just code.